## 過去の記録

### 2022年01月20日(木)

#### 統計数学セミナー

15:00-16:10   数理科学研究科棟(駒場) 号室

On weak factor models
[ 講演概要 ]

[ 参考URL ]

### 2022年01月19日(水)

#### 数理人口学・数理生物学セミナー

15:00-16:00   オンライン開催

(Japanese)
[ 講演概要 ]

しばしば時間遅れ, 宿主の免疫反応などが関係していることが多いが,

いは数個減少する効果が振動に関係することもある。

また, 以前にさかのぼり, さまざまな場合における安定性の議論について
も振り返る。

[ 参考URL ]
オンラインですので，参加希望のかたは稲葉(inaba@ms.u-tokyo.ac.jp)へご連絡ください．

#### 統計数学セミナー

14:30-16:00   数理科学研究科棟(駒場) 号室
Martin Hazelton 氏 (Otago University)
Dynamic fibre samplers for linear inverse problems
[ 講演概要 ]
Asia-Pacific Seminar in Probability and Statistics (APSPS)

Statistical inverse problems occur when we wish to learn about some random process that is observed only indirectly. Inference in such situations typically involves sampling possible values for the latent variables of interest conditional on the indirect observations. For count data, the latent variables are constrained to lie on a fibre (solution set for the linear system) comprising the integer lattice within a convex polytope.

Sampling the latent counts can be conducted using MCMC methods,through a random walk on this fibre. A major challenge is finding a set of basic moves that ensures connectedness of the walk over the fibre. In principle this can be done by computing a Markov basis of potential moves, but the resulting sampler can be hugely inefficient even when such a basis is computable. In this talk I will describe some current work on developing a dynamic Markov basis that generates moves on the fly. This approach can guarantee irreducibility of the sampler while gaining efficiency by increasing the probability of selecting serviceable sampling directions.
[ 参考URL ]

### 2022年01月18日(火)

#### 作用素環セミナー

16:45-18:15   オンライン開催

C$^*$-simplicity of relative profinite completions of generalized Baumslag-Solitar groups

[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

#### 東京名古屋代数セミナー

15:00-16:30   オンライン開催
オンライン開催の詳細は下記URLをご覧ください。

Exact-categorical properties of subcategories of abelian categories 1 (Japanese)
[ 講演概要 ]
Quillen's exact category is a powerful framework for studying extension-closed subcategories of abelian categories, and provides many interesting questions on such subcategories.
In the first talk, I will explain the basics of some properties and invariants of exact categories (e.g. the Jordan-Holder property, simple objects, and Grothendieck monoid).
In the second talk, I will give some results and questions about particular classes of exact categories arising in the representation theory of algebras (e.g. torsion(-free) classes over path algebras and preprojective algebras).
If time permits, I will discuss questions of whether these results can be generalized to extriangulated categories (extension-closed subcategories of triangulated categories).
[ 参考URL ]
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html

#### Lie群論・表現論セミナー

17:00-18:00   数理科学研究科棟(駒場) On line号室

[ 講演概要 ]

### 2022年01月13日(木)

#### 情報数学セミナー

16:50-18:35   オンライン開催

[ 講演概要 ]
(Zoom参加のお申し込みは下記のURLから）

[ 参考URL ]

### 2022年01月11日(火)

#### 作用素環セミナー

16:45-18:15   オンライン開催

Rationality for operators in free semicircular elements
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

#### トポロジー火曜セミナー

17:00-18:00   オンライン開催
Lie 群論・表現論セミナーと合同。 参加を希望される場合は、セミナーのウェブページをご覧下さい。

[ 講演概要 ]

[ 参考URL ]
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html

#### Lie群論・表現論セミナー

17:00-18:00   数理科学研究科棟(駒場) on line号室
トポロジー火曜セミナーと合同．

[ 講演概要 ]
アブストラクト：等質空間$G/H$とその不連続群$\Gamma\subset G$に対し, 商多様体$\Gamma\backslash G/H$ は$G/H$のClifford-Klein形と呼ばれる. Clifford-Klein形の研究において, コンパクトClifford-Klein形を持つ等質空間の分類問題は1980年代に小林俊行氏によって提起された重要な未解決問題である.
この問題を, 符号(n,2)の分解不可能かつ可約な擬リーマン対称空間に対して考察する. いくつかの系列の対称空間に対し, コンパクトClifford--Klein形の非存在を示し, また, 可算無限個の5次元(符号(3,2))の対称空間に対し, 新たに見つかったコンパクトClifford-Klein形を実際に構成する.

### 2022年01月06日(木)

#### 情報数学セミナー

16:50-18:35   オンライン開催

[ 講演概要 ]
(Zoom参加のお申し込みは下記のURLから）
2020 年代を迎えた最初の1 年に、世界はコロナ禍の影響による不連続な変化に直面した。一方で、このような危機への対応を通じ、結果として人々のデジタル技術の活用は加速し、サイバー空間は、我々の生活におけるある種の「公共空間」として、より一層の重みを持つようになってきている。
日本政府は、このような背景の下、 2021年、次期サイバーセキュリティ国家戦略を策定した。本講義では、その概要について述べる。
[ 参考URL ]

### 2021年12月23日(木)

#### 情報数学セミナー

16:50-18:35   オンライン開催

[ 講演概要 ]
(Zoom参加のお申し込みは下記のURLから）
最近、防衛省関連企業へのサイバー攻撃事件が多発している。ECと検索エンジンの世界最大手企業とサイバーセキュリティの最もホットな話題であるスタートアップ企業が、「誰も信用しないゼロトラストネットワーク」に注力している。
[ 参考URL ]

### 2021年12月22日(水)

#### 代数学コロキウム

17:00-18:00   オンライン開催
Stefano Morra 氏 (Paris 8 University)
Some properties of the Hecke eigenclasses of the mod p-cohomology of Shimura curves (English)
[ 講演概要 ]
The mod p local Langlands program, foreseen by Serre and proposed in precise terms by C. Breuil after his p-divisible groups computations in the Breuil-Conrad-Diamond-Taylor proof of the Shimura-Taiyama-Weil conjecture, was realized in the particular case of GL_2(\mathbf{Q}_p) thanks to a vast convergence of new tools: classification of mod p-representations of GL_2(\mathbf{Q}_p), local Galois deformation techniques, local-global compatibility arguments.
When trying to extend these conjectures to more general groups, multiple problems arise (lack of classification results for smooth mod p-representations of p-adic groups, absence of explicit integral models for Galois representations with the relevant p-adic Hodge theory conditions), and the only way to formulate, and test, conjectures on a mod p local Langlands correspondence relies on its expected realization in Hecke eigenclasses of Shimura varieties (or, in other words, the expectation of a local-global compatibility of the Langlands correspondence).
In this talk we describe some properties of Hecke isotypical spaces of the mod p-cohomology of Shimura curves with infinite level at p, when the reflex field F is unramified at p and the Shimura curve arises from a quaternion algebra which is split at p. These Hecke isotypical spaces are expected to be the “good” smooth mod p-representations of GL_2(F_{\mathfrak{p}}) attached to mod p Galois representations of Gal(\overline{\mathbf{Q}_p}/F_{\mathfrak{p}}) via the expected local Langlands correspondence mod p. We will in particular comment on their Gelfand-Kirillov dimension, and their irreducibility (in particular, the finite length of these Hecke eigenspaces as GL_2(F_{\mathfrak{p}})-representations).
This is a report on a series of work joint with C. Breuil, F. Herzig, Y. Hu et B. Schraen.

### 2021年12月21日(火)

#### トポロジー火曜セミナー

17:30-18:30   オンライン開催
Lie 群論・表現論セミナーと合同。 参加を希望される場合は、セミナーのウェブページをご覧下さい。

Classification of holomorphic vertex operator algebras of central charge 24 (JAPANESE)
[ 講演概要 ]
Holomorphic vertex operator algebras are imporant in vertex operator algebra theory. For example, the famous moonshine vertex operator algebra is holomorphic. One of the fundamental problems is to classify holomorphic vertex operator algebras. It is known that holomorphic vertex operator algebras of central charge 8 and 16 are lattice vertex operator algebras. I will talk about recent progress on the classification of holomorphic vertex operator algebras of central charge 24.
[ 参考URL ]
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html

#### 作用素環セミナー

16:45-18:15   オンライン開催
Wojciech Dybalski 氏 (Adam Mickiewicz University in Poznan)
Interacting massless infraparticles in 1+1 dimensions
(English)
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

#### Lie群論・表現論セミナー

17:30-18:30   数理科学研究科棟(駒場) on line号室
トポロジー火曜セミナーと合同。

Classification of holomorphic vertex operator algebras of central charge 24
(Japanese)
[ 講演概要 ]
Holomorphic vertex operator algebras are important in vertex operator algebra theory. For example, the famous moonshine vertex operator algebra is holomorphic.
One of the fundamental problems is to classify holomorphic vertex operator algebras. It is known that holomorphic vertex operator algebras of central charge 8 and 16 are lattice vertex operator algebras.
I will talk about recent progress on the classification of holomorphic vertex operator algebras of central charge 24.

### 2021年12月17日(金)

#### 談話会・数理科学講演会

15:30-16:30   オンライン開催

Jun-Muk Hwang 氏 (Center for Complex Geometry, IBS, Korea)
Growth vectors of distributions and lines on projective hypersurfaces (ENGLISH)
[ 講演概要 ]
For a distribution on a manifold, its growth vector is a finite sequence of integers measuring the dimensions of the directions spanned by successive Lie brackets of local vector fields belonging to the distribution. The growth vector is the most basic invariant of a distribution, but it is sometimes hard to compute. As an example, we discuss natural distributions on the spaces of lines covering hypersurfaces of low degrees in the complex projective space. We explain the ideas in a joint work with Qifeng Li where the growth vector is determined for lines on a general hypersurface of degree 4 and dimension 5.

### 2021年12月16日(木)

#### 応用解析セミナー

16:00-17:00   オンライン開催
Zhanpeisov Erbol 氏 (東大数理)
Existence of solutions for fractional semilinear parabolic equations in Besov-Morrey spaces (Japanese)
[ 講演概要 ]

[ 参考URL ]
https://forms.gle/whpkgAwYvyQKQMzM8

#### 東京名古屋代数セミナー

16:45-18:15   オンライン開催
オンライン開催の詳細は下記URLをご覧ください。
Nicholas Williams 氏 (University of Cologne)
Cyclic polytopes and higher Auslander-Reiten theory (English)
[ 講演概要 ]
Oppermann and Thomas show that tilting modules over Iyama’s higher Auslander algebras of type A are in bijection with triangulations of even-dimensional cyclic polytopes. Triangulations of cyclic polytopes are partially ordered in two natural ways known as the higher Stasheff-Tamari orders, which were introduced in the 1990s by Kapranov, Voevodsky, Edelman, and Reiner as higher-dimensional generalisations of the Tamari lattice. These two partial orders were conjectured to be equal in 1996 by Edelman and Reiner, and we prove that this conjecture is true. We further show how the higher Stasheff-Tamari orders correspond in even dimensions to natural orders on tilting modules which were studied by Riedtmann, Schofield, Happel, and Unger. This then allows us to complete the picture of Oppermann and Thomas by showing that triangulations of odd-dimensional cyclic polytopes correspond to equivalence classes of d-maximal green sequences, which we introduce as higher-dimensional analogues of Keller’s maximal green sequences. We show that the higher Stasheff-Tamari orders correspond to natural orders on equivalence classes of d-maximal green sequences, which relate to the no-gap conjecture of Brustle, Dupont, and Perotin. The equality of the higher Stasheff-Tamari orders then implies that these algebraic orders on tilting modules and d-maximal green sequences are equal. If time permits, we will also discuss some results on mutation of cluster-tilting objects and triangulations.
[ 参考URL ]
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html

#### 情報数学セミナー

16:50-18:35   オンライン開催

[ 講演概要 ]
(Zoom参加のお申し込みは下記のURLから）
最近、自動車会社に関連するサプライチェーンへのサイバー攻撃事件が多発している。世界的ネットワーク機器企業とサイバーセキュリティの最もホットな話題であるスタートアップ企業が、「誰も信用しないゼロトラストネットワーク」に注力している。
そこで、本講では、自動車会社サプライチェーンへのサイバー攻撃の本質と、シスコシステムズとサイバーセキュリティベンチャー企業（ SentinelOne社 StackPath社）の動向とその技術について概観する。
[ 参考URL ]

### 2021年12月15日(水)

#### 統計数学セミナー

14:30-16:00   数理科学研究科棟(駒場) 号室
Estate Khmaladze 氏 (Victoria University of Wellington)
Theory of Distribution-free Testing
[ 講演概要 ]
Asia-Pacific Seminar in Probability and Statistics (APSPS)

The aim of the talk is to introduce transformations of empirical-type processes by a group of unitary operators. Recall that if v_{nP} is empirical process on real line, based on a sample from P, it can be mapped into empirical process v_{nQ} by appropriate change of time

v_{nP}(h(x))=v_{nQ}(x)

where h(x) is continuous and increasing. This is the basis for distribution-free theory of goodness of fit testing. If w(\phi) is a function-parametric “empirical-type” process (i.e. has functions \phi from a space L as a time) and if K* is a unitary operator on L, then transformed process Kw we define as
Kw(\phi) = w(K*\phi)

These two formulas have good similarity, but one transformation in on the real line, while the other transformation in on functional space.This later one turns out to be of very broad use, and allows to base distribution-free theory upon it. Examples, we have specific results for, are parametric empirical
processes in R^d, regression empirical processes, those in GLM, parametric models for point processes and for Markov processes in discrete time. Hopefully, further examples will follow.
[ 参考URL ]

### 2021年12月14日(火)

#### 作用素環セミナー

16:45-18:15   オンライン開催
Karen Strung 氏 (Czech Academy of Science)
Constructions in minimal amenable dynamics and applications to classification of $C^*$-algebras

[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

#### Lie群論・表現論セミナー

17:00-18:00   数理科学研究科棟(駒場) on line号室

Conley 指数の定義について
(Japanese)
[ 講演概要 ]
Conley 指数は位相力学系の局所的な振る舞いを記述する量である。本講演では Conley 指数理論の新しい枠組みを紹介する。議論は非常に初等的で、位相空間論と、集合の包含関係の計算しか使わない。

### 2021年12月13日(月)

#### 複素解析幾何セミナー

10:30-12:00   オンライン開催

A generalized Hermitian curvature flow on almost Hermitian manifolds (Japanese)
[ 講演概要 ]
It is well-known that the Uniformization theorem (any Riemannian metric on a closed 2-manifold is conformal to one of constant curvature) can be proven by using the Ricci flow. J. Streets and G. Tian questioned whether or not a geometric flow can be used to classify non-Kähler complex surfaces as in the case of the Ricci flow. Also they asked if it is possible to prove classification results in higher dimensions by using geometric flows in non-Kähler Hermitian geometry. Streets and Tian considered that these flows should be close to the Kähler-Ricci flow as much as possible. From this point of view, they introduced a geometric flow called the Hermitian curvature flow (HCF) which evolves an initial Hermitian metric in the direction of a Ricci-type tensor of the Chern connection modified with some lower order torsion terms. Streets and Tian also introduced another geometric flow, which is called the pluriclosed flow (PCF), by choosing torsion terms to preserve the pluriclosed condition on Hermitian metrics. Y. Ustinovskiy studied a particular version of the HCF over a compact Hermitian manifold. Ustinovskiy proved that if the initial metric has Griffiths positive (non-negative) Chern curvature, then this property is preserved along the flow.

In recent years, some results concerning geometric flows on complex manifolds have been extended to the almost complex setting. For instance, L. Vezzoni defined a new Hermitian curvature flow on almost Hermitian manifolds for generalizing some studies on the HCF and the Hermitian Hilbert functional. And J. Chu, V. Tosatti and B. Weinkove considered parabolic Monge-Ampère equation on almost Hermitian manifolds, which is equivalent to the almost complex Chern-Ricci flow. T. Zheng characterized the maximal existence time for a solution to the almost complex Chern-Ricci flow.

In this talk, we consider a generalized Hermitian curvature flow in almost Hermitian geometry and introduce that it has some properties such as the long-time existence obstruction, the uniform equivalence between its solution and an almost Hermitian metric, and the preservation result along the flow.
[ 参考URL ]
https://u-tokyo-ac-jp.zoom.us/meeting/register/tJ0vcu2rrDIqG9Rv5AT0Mpi37urIkJ1IRldB

### 2021年12月09日(木)

#### 情報数学セミナー

16:50-18:35   オンライン開催

[ 講演概要 ]
(Zoom参加のお申し込みは下記のURLから）
最近、携帯電話会社の運営する口座とリンクした銀行口座を悪用した不正引き出し事件が多発している。世界的ソフトウェア企業とサイバーセキュリティの最もホットな話題であるスタートアップ企業が、「誰も信用しないゼロトラストネットワーク」に注力している。
そこで、本講では、不正引き出し事件の本質と、マイクロソフトとサイバーセキュリティベンチャー企業（ Cybereason社とHashiCorp社 ）の動向とその技術について概観する。
[ 参考URL ]